The invention relates to improvements in apparatus for transporting and treating fibrous materials, such as particles of natural, substitute or reconstituted tobacco, fibrous filter material for tobacco smoke and the like. More particularly, the invention relates to improvements in apparatus which can be utilized in so-called distributors or hoppers of machines for making cigarette rods, cigar rods, cigarillo rods, rods of fibrous filter material and like products of the tobacco processing industry.
It is well known to employ air as a carrier medium for tobacco and other particulate materials which are used in the tobacco processing industry. For example, an air stream can be used to transport a shower of tobacco particles toward a foraminous belt conveyor which gathers a growing tobacco stream for advancement toward and through a trimming or equalizing station where the surplus of tobacco is removed and the remainder of the stream is ready to be converted into a rod-like filler. It is further known to employ streams of air as a means for transporting comminuted tobacco leaves or the like through a classifying or sifting zone where the satisfactory particles (such as shreds of tobacco leaf laminae) are segregated from unsatisfactory constituents, e.g., from relatively heavy and large fragments of tobacco ribs which would be likely to puncture a wrapper of cigarette paper or the like. Air can be used to convey particles of tobacco or the like in the form of a stream (e.g., by causing the particles to adhere to one side of a foraminous belt conveyor or to the periphery of a foraminous drum-shaped conveyor) or in the form of a shower, e.g., by causing the particles to rise with an ascending air stream.